Text subtitle decoder and method for decoding text subtitle streams

ABSTRACT

A text subtitle decoder includes a text subtitle processor, a text renderer, and a presentation controller. The text subtitle processor parses a text subtitle stream into text data and reproduction control information, where the text data represent a subtitle text to be displayed within a text subtitle region. After the text subtitle stream is parsed, the text renderer renders the text data into bitmap data using the reproduction control information. The presentation controller controls operations of the text subtitle processor and the text renderer.

DOMESTIC PRIORITY INFORMATION

This is a continuation of U.S. application Ser. No. 10/957,578 filedOct. 5, 2004 now U.S. Pat. No. 7,593,060; the contents of which arehereby incorporated by reference in their entirety.

FOREIGN PRIORITY INFORMATION

The present invention claims priority under 35 U.S.C. 119 on KoreanApplication No. 10-2004-0006990, filed Feb. 3, 2004; the contents ofwhich are hereby incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a text subtitle decoder and a methodfor decoding text subtitle streams recorded in an optical disc.

2. Discussion of the Related Art

Optical discs are widely used as an optical recording medium forrecording mass data. Presently, among a wide range of optical discs, anew high density optical recording medium (HD-DVD), such as the Blu-rayDisc (hereafter referred to as “BD”), is under development for writingand storing high definition video and audio data for a long period oftime. Currently, global standard technical specifications of the Blu-rayDisc (BD), which is known to be the next generation HD-DVD technology,are under establishment as a next generation optical recording solutionthat is able to have a data significantly surpassing the conventionalDVD, along with many other digital apparatuses.

Accordingly, optical reproducing apparatuses having the Blu-ray Disc(BD) standards applied thereto are also being developed. However, sincethe Blu-ray Disc (BD) standards are yet to be completed, there have beenmany difficulties in developing a complete optical reproducingapparatus. Particularly, in order to effectively reproduce the data fromthe Blu-ray Disc (BD), not only should the main AV data as well asvarious data required for a user's convenience, such as subtitleinformation as the supplementary data related to the main AV data, beprovided, but also managing information for reproducing the main dataand the subtitle data recorded in the optical disc should be systemizedand provided.

However, in the present Blu-ray Disc (BD) standards, since the standardsof the supplementary data, particularly the subtitle information, arenot completely consolidated, there are many restrictions in thefull-scale development of a Blu-ray Disc (BD) basis optical reproducingapparatus. And, such restrictions cause problems in providing thesupplementary data such as subtitles to the user.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a recording medium forreproduction of text subtitle streams, and methods and apparatuses forrecording and reproducing the same, all of which substantially obviateone or more problems due to limitations and disadvantages of the relatedart.

An object of the present invention is to define specific reproductioncontrol information in a text subtitle stream such that text data for atext subtitle included in the text subtitle stream could be reproducedin a standardized manner.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

In one aspect of the present invention, a text subtitle decoder includesa text subtitle processor, a text renderer, and a presentationcontroller. The text subtitle processor parses a text subtitle streaminto text data and reproduction control information. The text datarepresents a subtitle text to be displayed within a text subtitleregion. The text renderer renders the text data into bitmap data usingthe reproduction control information, and the presentation controllercontrol operations of the text subtitle processor and the text renderer.The reproduction control information may include region styleinformation which specifies a region style of the text subtitle regionincluding an overall font-related style of the text data. The regionstyle of the text subtitle region may be specified by at least one of aregion position, a region size, a region background color, a textposition, a text flow, a text alignment, a line space, a fontidentification, a font style, a font size, and a font color defined inthe region style information. In addition, the text subtitle processormay further parse the text subtitle stream into inline information forapplying a different font-related style to a selected portion of thetext data.

In another aspect of the present invention, a method for decoding textsubtitle streams recorded in a recoding medium includes the steps ofparsing a text subtitle stream into text data and reproduction controlinformation, and rendering the text data into bitmap data using thereproduction control information. The text data represent a subtitletext to be displayed within a text subtitle region. The reproductioncontrol information may include region style information specifying aregion style of the text subtitle region including an overallfont-related style of the text data. The region style of the textsubtitle region may be specified by at least one of a region position, aregion size, a region background color, a text position, a text flow, atext alignment, a line space, a font identification, a font style, afont size, and a font color defined in the region style information. Theabove method may further include the step of parsing the text subtitlestream into inline information for applying a different font-relatedstyle to a selected portion of the text data.

In a further aspect of the present invention, a system for decoding textsubtitle streams recorded on a recording medium includes a text subtitledecoder, a graphics plane, and a color look up table. The text subtitledecoder parses a text subtitle stream into text data and reproductioncontrol information and renders the text data into bitmap data using thereproduction control information. Thereafter, the graphics planeconverts the bitmap data into displayable images and the color look uptable controls at least one of color and transparency levels of thedisplayable images.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiments of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates an optical (e.g., Blu-ray) disc player according tothe present invention;

FIG. 2A illustrates data files recorded in an optical disc according tothe present invention;

FIG. 2B illustrates data storage areas of an optical disc according tothe present invention;

FIGS. 3A and 3B illustrate examples of a text subtitle region displayedon a display screen according to the present invention;

FIG. 4 illustrates an apparatus for decoding AV streams and textsubtitle streams according to the present invention;

FIG. 5A illustrates an example of a page composition segment (PCS)information included in a text subtitle stream according to the presentinvention;

FIG. 5B illustrates an example of an object definition segment (ODS)information included in a text subtitle stream according to the presentinvention;

FIGS. 6A to 6D illustrate several examples of the text subtitle decodershown in FIG. 4 according to the present invention; and

FIG. 7 illustrates an apparatus of recording and/or reproducing textsubtitle streams according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

In this description, main data represent audio/video (AV) data that arerecorded on an optical disc by an author and belong to a title (e.g., amovie title). In general, the AV data are recorded in MPEG2 format andare often called AV streams or main AV streams. In addition,supplementary data represent all other data associated with reproductionof the main data, examples of which are text subtitle streams, graphicstreams, menu information, and supplementary audio streams (e.g., for abrowsable slideshow). These supplementary data streams may be recordedin MPEG2 format or any other data format, and they could be multiplexedwith the AV streams or exist as independent data files in a same ordifferent data area within the optical disc.

According to the present invention, a subtitle represents captioninformation for images being reproduced and is often represented in apredetermined language. For example, when a user selects an option forviewing one of a plurality of subtitles for multiple languages whileviewing images on display screen, caption information corresponding tothe selected option is displayed on a predetermined portion of thedisplay screen. The caption information may be recorded in an opticaldisc as MPEG2 transport packets, bitmap graphics, or text data. When thecaption information is text data, the subtitle is called a textsubtitle. A text subtitle stream includes text data for a text subtitleand reproduction control information for the text data. According to oneexample the present invention, a text subtitle stream may be recorded inan optical disc and exist as an independent stream file. In addition,the text subtitle stream may be downloaded from an external data source.

FIG. 1 illustrates an optical disc player 1 according to the presentinvention. The disc player 1 is able to reproduce text subtitle streamsand audio/video (AV) streams recorded in an optical disc, an example ofwhich is a Blu-ray disc. Also, the disc player 1 is also able to recordtext subtitle streams and AV streams on an optical disc.

In addition, the disc player 1 according to the present invention isable to receive or download input data from an external data source,examples of which are a digital television broadcasting station and theInternet server. After the disc player 1 performs the requireddata-processes for the input data, it displays the processed signals ona display device 2 coupled to the disc player 1. Therefore, the discplayer 1 is able to receive AV streams and text subtitle streams fromthe optical disc or the external data source, respectively, and toreproduce AV streams and the text subtitle data simultaneously. The textsubtitle data may be in MPEG format, text, XML, or HTML format.

FIG. 2A illustrates data files recorded in a Blu-ray (BD) disc accordingto the present invention. Referring to FIG. 2A, at least one BDdirectory (BDMV) is included in a root directory (root). Each BDdirectory includes an index file (e.g., index.bdmv) and an object file(e.g., MovieObject.bdmv), which represent general files that are usedwhen interacting with one or more users. For example, the index filecontains data representing an index table which includes variousinformation regarding a plurality of selectable menus and titles.

Each BD directory includes three file directories including data to bereproduced, and information required for reproducing the data. The filedirectories included in each BD directory are a stream directory(STREAM), a playlist directory (PLAYLIST), and a clip informationdirectory (CLIPINF).

The stream directory includes audio/video (AV) stream files andsupplementary stream files including one or more text subtitle streamfiles. The main AV streams and the text subtitle streams may be in theform of MPEG2 transport packets and be named as “*.m2ts”, as shown inFIG. 2A. The text subtitle stream files exist as independent streamfiles within the stream directory. In addition, the text subtitle streamfiles could be in other data format and be named according to their dataformat. For example, if the text subtitle stream files are in textformat, they could be named as “*.txt.”

Next, the clip information directory includes clip information files(*.clpi) that correspond to the AV and text subtitle stream filesincluded in the stream directory. A clip information file includesproperty information and timing information of a corresponding streamfile, where timing information includes mapping information that mapspresentation time stamp (PTS) with source packet number (SPN) usingentry point map. In the industry standard, each pair of a stream fileand its corresponding clip information file is designated as a clip. Forexample, 01000.clpi included in CLIPINF includes the property and timinginformation of 01000.m2ts included in STREAM, and 01000.clpi and01000.m2ts form a clip.

Referring back to FIG. 2A, the playlist directory includes one or morePlayList files (*.mpls), wherein each PlayList file includes at leastone PlayItem which designates at least one main AV clip and thereproduction time for the main AV clip. More specifically, a PlayItemincludes information designating beginning and ending times (In-Time andOut-Time) for reproduction of a main AV clip, which may be designated byClip_Information_File_Name within the PlayItem. Therefore, a PlayListfile represents the basic reproduction control information for one ormore main AV clips. In addition, the PlayList file may further includesa SubPlayItem, which is the basic reproduction control information ofone or more text subtitle stream files. When a SubPlayItem is includedin a PlayList file to reproduce one or more text subtitle streams, theSubPlayItem is often synchronized with PlayItem(s) also included in thePlayList file. In addition, when the SubPlayItem is used to reproduce abrowsable slideshow, it may not be synchronized with the PlayItem(s).

FIG. 2B illustrates data storage areas of an optical disc, in which thedata files shown in FIG. 2A are recorded. As shown in the figure, thedisc volume includes a file system information area occupying the inmostportion of the disc volume, a stream area occupying the outmost portionof the disc volume, and a database area occupied between the file systeminformation area and the stream data area. In the file systeminformation area, system information for managing the entire data filesis recorded. Next, AV streams and one or more text subtitle streams areprerecorded in the stream area. The general files, PlayList files, andclip information files are recorded in the database area of the discvolume. As discussed above, the general files include an index file andan object file, and the PlayList files and clip information filesinclude information required to reproduce the AV streams and textsubtitle streams recorded in the stream area. A user is able to select aspecific play-back mode and to reproduce desired main and supplementalstreams in the selected play-back mode using the information stored inthe database area and/or stream area.

FIGS. 3A and 3B illustrate examples of a text subtitle displayed on adisplay screen 2 according to the present invention. A text subtitlestream recorded on an optical disc includes data representing a subtitletext (e.g., characters). When the text subtitle stream is reproduced, atext subtitle region including the text data is displayed on the displayscreen 2, as shown in both figures. The text data included within thetext subtitle region shown in FIG. 3A is in Korean, and the text datadisplayed within the region shown in FIG. 3B is in English. In order tosupport both languages, there are more than one independent textsubtitle files recorded in the optical disc.

In conclusion, one or more text subtitle streams according to thepresent invention may be provided from an optical disc, in which thetext subtitle streams exist as one or more text subtitle stream files.Or, they could be provided from an external data source, as shown inFIG. 1. The text subtitle streams may be in MPEG format or any otherdata format (e.g., text format).

FIG. 4 illustrates an apparatus of decoding AV streams and text subtitlestreams according to the present invention. The apparatus includes apacket identifier (PID) filter 5 for separating input streams into videostreams, audio streams, graphic streams, and text subtitle streams basedon their packet identifiers, an audio decoding part 10 for decoding theaudio streams, a video decoding part 20 for decoding the video streams,a graphic decoding part decoding the graphic streams, and a textsubtitle decoding part 40 for decoding the text subtitle streams.

The text subtitle streams may be extracted from an optical disc, or theycould be inputted from an external data source. For this reason, theapparatus shown in FIG. 4 includes a switch 6 which selects a datasource. For example, if a text subtitle stream in MPEG format isextracted from the optical disc, the switch 6 selects data line Aconnected to the PID filter 5. On the other hand, if a text subtitlestream in other format (e.g., text, XML, or HTML format) is inputtedthrough the external source, the switch 6 selects data line B which isconnected to the external source.

Each of the audio decoding part 10, video decoding part 20, and graphicdecoding part 30 includes a transport buffer 11, 21, and 31 for storinga predetermined size of data streams to be decoded. A video plane 23 anda graphics plane 33 are included in the video decoding part 20 and thegraphic decoding part 30, respectively, for converting decoded signalsinto displayable images. The graphic decoding part 30 further includes acolor look up table (CLUT) 34 for controlling color and transparencylevels of the displayable images.

When the text subtitle decoding part 40 receives one or more textsubtitle streams from the switch 6, all of these streams are initiallypreloaded into a subtitle preloading buffer (SPB) 41 at once. Assuming atypical size of a text subtitle stream file for a single language isabout 0.5 megabytes, the size of the subtitle preloading buffer 41should be greater than 0.5 megabytes. In order to ensure seamlesspresentation of a text subtitle when a user switches among subtitlestream files supporting multi-languages, the size of the subtitlepreloading buffer 41 should be determined based on the a total number ofthe text subtitle stream files. The buffer size must be large enough topreload all the required text subtitle stream files at once. Since allthe text subtitle stream files are preloaded into the subtitlepreloading buffer 41, extraction and use of the text subtitle streamscan be done in a time-efficient manner. Also, the control of thesubtitle preloading buffer 41 could be quite simple due to the reasonset forth.

The text subtitle decoding part 40 further includes a text subtitle(TXT_ST) decoder 42 which decodes one or more text subtitle streamsstored in the subtitle preloading buffer 41, a graphics plane 43 forconverting the decoded subtitle stream(s) into displayable images, and acolor look up table (CLUT) 44 for controlling the color and transparencylevels of the converted images.

An image superimposition part 50 included in the apparatus shown in FIG.4 combines the images outputted from the video decoding part 20, thegraphic decoding part 30, and the text subtitle decoding part 40. Thesecombined images are displayed on a display screen. The video imagesoutputted from the video plane 23 of the video decoding part 20 aredisplayed as a background of the display screen, and the imagesoutputted from the graphic decoding part 30 and/or the text subtitledecoding part 40 are superimposed over the displayed video images. Forexample, if the output images of the graphic decoding part 30 areinteractive graphic images, the text subtitle images outputted form thetext subtitle decoding part 40 are initially superimposed over the videoimages by a first adder 52. Thereafter, the interactive graphic imagesare further superimposed over the subtitle-superimposed images by asecond adder 53. On the other hand, if the output images of the graphicdecoding part 30 are presentation graphic images, these images areinitially superimposed over the video images from the video decodingpart 20 by the first adder 52, and the text subtitle images from thetext subtitle decoding part 40 are further superimposed over the videoimages by the second adder 53.

The apparatus shown in FIG. 4 further includes a system decoder 4 fordecoding input data streams extracted from an optical disc, and amicroprocessor 3 for controlling operations of all the mentionedcomponents of the apparatus.

Reference will now be made in detail to specific information/dataincluded in a text subtitle stream according to the present invention. Atext subtitle stream file recorded on an optical disc according to thepresent invention includes a page composition segment (PCS) informationincluding region (global) style information, and an object definitionsegment (ODS) information including data representing a subtitle text(e.g., characters) and inline (local) style information. When the textsubtitle stream file is reproduced, a text subtitle region including thesubtitle text is displayed on a display screen according to the regionstyle information and the inline style information.

An example of the page composition segment (PCS) information isillustrated in FIG. 5A. An object defined in the PCS informationrepresents a text subtitle region (page) and an entire portion of thetext included in the text subtitle region. The PCS information includesobject composition information (composition_object (*)) including objectidentification (object_id), object position information(object_position_info), and object cropping information(object_cropping_info) for an object. The PCS information furtherincludes information specifying a style of the text subtitle regiondisplayed within the display screen, and this information is oftendenoted as region style information or global style information (globalstyle_page shown in FIG. 5A). For simplicity, it will be referred to asregion style information.

The region style information specifies a region style of a text subtitleregion including a subtitle text, where the region style includes anoverall font-related style of the subtitle text included within the textsubtitle region. For example, the region style information specifies theregion style by defining a plurality of display properties required fordisplaying the text subtitle region including subtitle text on thedisplay screen. For example, the region style information may define aregion position (region_position) indicating at least one of thehorizontal and vertical positions of the text subtitle region from anorigin of the display screen, a region size (region_size) indicating atleast one of a width and height of the text subtitle region, and aregion background color (region_background_color) indicating abackground color of the text subtitle region. The region styleinformation may further define a text position (text_position)indicating a position of the text data within the text subtitle region,a text flow (text_flow) indicating at least one a character progression(left-to-right or right-to-lest) and a line progression (top-to-bottomor bottom-to-top) of the text data within the text subtitle region, atext alignment (text_alignment) indicating one of left, center, rightalignment of the text data within the text subtitle region, a line space(line_space) indicating a distance between two adjacent baselines of thetext data within the text subtitle region. The region style informationcould also define other display properties not mentioned above.

The region style information further specifies the region style bydefining an overall font-related style (font-related display properties)of the subtitle text included in a text subtitle region. For example,the region style information may further define a font identification(font_id) indicating a value specifying a font file associated with thetext subtitle stream file including the region style information, a fontstyle (font_style) indicating at least one normal, bold, and italic fontstyles, a font size (font_size) indicating a vertical size of the textincluded in the text subtitle region (e.g., a character), and a fontcolor (font_color) indicating a color of the text. As described above,the overall font-related style of the subtitle text within the textsubtitle region is specified by at least one of the font identification,font style, font size, and font color defined in the region styleinformation.

FIG. 5B illustrates an example of the object definition segment (ODS)information included in a text subtitle stream. An object defined byobject identification (object_id) in the ODS information represents aselected portion of a subtitle text (e.g., characters) included in atext subtitle region. The ODS information includes object informationincluding object identification (object_id) and object versioninformation (object_version_number) for an object. The ODS informationfurther include information for applying a different font-related styleto a selected portion of the text included in a text subtitle, and thisinformation is often denoted as inline style information or local styleinformation (local style_object shown in FIG. 5B). For simplicity, itwill be referred to as inline style information.

An object of the local style information is to apply a differentfont-related style for a selected portion of the text included in a textsubtitle region. In other words, the local style information specifies aspecific font-related style of the selected text portion, which may bedifferent from the overall font-related style defined by the regionstyle information. For example, the inline style information specifiesthe specific font-related style by redefining at least one of a fontidentification (font_id) indicating a value specifying a different fontfile associated with the text subtitle stream, a font style (font_style)indicating a different font style, a font size (font_size) indicating adifferent font size, and a font color (font_color) indicating adifferent font color for the selected text portion within the textsubtitle region. In addition, the inline style information may furtherdefine various other font-related display properties not mentionedabove.

Referring back to FIG. 5B, the ODS information further includes data(Text_data) representing a subtitle text included in a text subtitleregion. This text data may be included object data information(Object_Data), which is included in object_data_fragment, as shown inFIG. 5B. However, the text data may be included in the ODS in othermanner.

A text subtitle stream file may further include palette information foruse with a color look up table (CLUT). This palette information may beincluded in palette definition segment (PDS) information furtherincluded in the text subtitle stream file, or it may be included in aclip information file corresponding to the text subtitle stream.Alternatively, the palette information may be included in the PCSinformation shown in FIG. 5A.

FIG. 6A illustrates a first example of the text subtitle decoder 42shown in FIG. 4 according to the present invention, where a textsubtitle stream is provided from an optical disc. The PCS informationand ODS information included in a text subtitle stream preloaded in thesubtitle preloading buffer (SPB) 41 may be initially arranged in theorder of their information type and be stored in a coded data buffer(EB) 410. However, this process is only for improving an overallefficiency of the text subtitle decoder 42, and it may be omitted.Therefore, the coded data buffer 410 is only for optional and may not beincluded in the text subtitle decoding part 40 shown in FIG. 6A.

Referring back to FIG. 6A, a text subtitle processor (TXT_ST parser) 411included in the text subtitle (TXT_ST) decoder 42 parses the PCS and ODSinformation, which are preloaded in the subtitle preloading buffer (SPB)41 or in the coded data buffer (EB) 410, into data representing asubtitle text (text data) to be included in a text subtitle region,inline style information, and region style information. When the PCS andODS information are parsed by the text subtitle parser 411, the textdata and the inline information are transferred to a text renderer 412and the region style information is transferred to a composition buffer(CB) 414. Thereafter, the text renderer 412 renders the text data intobitmap data under control of a presentation (color/layout/composition)controller 415 using the region style information, the inline styleinformation, and a font file. The font file may be extracted from anoptical disc or a memory (not illustrated) included in the optical discplayer 1 shown in FIG. 1.

The composition buffer (CB) 414 stores the region style informationparsed by the text subtitle parser 411 and provides this information tothe presentation controller 415. An object buffer (DB) 413 temporarilystores the bitmap data outputted from the text renderer 412 and outputsthe stored data according to time information (e.g., presentation timestamps). The presentation controller 415 controls operations of the textrenderer 412 and the object buffer (DB) 413 according to the regionstyle information, the inline style information, a corresponding clipinformation file, and a user input.

FIG. 6B illustrates a second example of the text subtitle decoder 42shown in FIG. 4 according to the present invention, wherein a textsubtitle stream is provided from an optical disc. The text subtitledecoder 42 shown in FIG. 6B does not include an object buffer and acomposition buffer. A text subtitle processor (TXT_ST parser) 421 parsesthe text subtitle stream including PCS and ODS information into subtitletext data, inline style information, and region style information. WhenPCS and ODS information are parsed, the text data and inline styleinformation are directly transferred to a text renderer 422 and theregion style information is directly transferred to a presentation(color/layout/composition) controller 423. Thereafter, the text renderer422 renders the text data into bitmap data under control of thepresentation controller 423 using the region style information, inlinestyle information, and a font file. The bitmap data is directlydisplayed through the graphics plane 43. Since the storing processes ofthe bitmap data and the region style information are omitted, theoverall data process of the text subtitle decoder 42 is greatlysimplified.

FIGS. 6C and 6D illustrate a third and fourth example of the textsubtitle decoder 42 shown in FIG. 4 according to the present invention,where a text subtitle stream is provided from an external data sourcerather than from an optical disc. When a text subtitle stream includesdata representing a subtitle text (text data) in XML or HTML format, thetext data may include tag information (often referred to as “mark-upsyntax”) indicating property information of the text data. In the thirdexample of the text subtitle decoder 42, pseudo-PCS (page compositionsegment) information and pseudo-ODS (object definition segment)information are created from the mark-up syntax. On the other hand, themark-up syntax is directly used when reproducing or decoding the textsubtitle stream. For this reason, the operations of the third and fourthexamples of the text subtitle decoder 42 will be similar, in certainaspect, to those of the first and second examples shown in FIGS. 6A and6B.

Referring to FIG. 6C, a text subtitle processor (TXT_ST parser orsegment converter) 431 included in the text subtitle decoder 42 convertsa text subtitle stream originally provided from the external data sourceinto standardized information. For example, if the text subtitle streamis in XML format, it initially converts the data into pseudo-PCSinformation and pseudo-ODS information including subtitle text data, andparses these information into the text data, inline style information,and region style information. When the pseudo-PCS and pseudo-ODSinformation are parsed, the text data and inline style information aretransferred to a text renderer (a bitmap generator) 432, and the regionstyle information is transferred to a composition buffer (CB) 434.Thereafter, the text renderer 432 renders the text data into bitmap dataunder control of a graphic controller 435 using the region styleinformation, the inline style information, and a font file. The fontfile may be extracted from an optical disc or a memory (not illustrated)included in the optical disc player 1 shown in FIG. 1.

The composition buffer 434 stores the region style information parsed bythe text subtitle parser 431 and provides this information to thegraphic controller 435. An object buffer (DB) 433 temporarily stores thebitmap data outputted from the text renderer 432 and outputs the storeddata according to time information (e.g., presentation time stamps). Thegraphic controller 435 controls operations of the text renderer 432 andthe object buffer 433 according to the region style information, theinline style information, a corresponding clip information file, and auser input.

Referring to FIG. 6D, a text subtitle processor (TXT_ST parser) 441included in the text subtitle decoder 42 converts a text subtitle streamoriginally provided from the external data source into standardizedinformation. For example, if the text subtitle stream is in XML or HTMLformat, it initially converts the data into pseudo-PCS information andpseudo-ODS information including subtitle text data, and parses theseinformation into the text data, inline style information, and regionstyle information. When the pseudo-PCS and pseudo-ODS information areparsed, the text data and inline style information are transferred to atext renderer (442), and the region information style information istransferred to a graphic controller 443. Thereafter, the text renderer442 renders the text data into bitmap data under control of the graphiccontroller 443 using the region style information, the inline styleinformation, and a font file. The converted bitmap data issimultaneously displayed through the graphics plane 43. Since thestoring processes of the bitmap data and the region style informationare not required, the overall data process of the text subtitle decoder42 is greatly simplified.

FIG. 7 illustrates an apparatus of recording or reproducing textsubtitle streams according to the present invention. The apparatus shownin FIG. 7 includes a pickup unit 11 that reads AV streams and one ormore text subtitle streams from an optical disc. The pickup unit 11 isalso able to record AV streams and one or more text subtitle streamsinto an optical disc. Each text subtitle stream being recorded on orread from the optical disc by the pickup unit 11 includes datarepresenting a subtitle text (text data) to be displayed within a textsubtitle region of a display screen, region (global) style informationspecifying a region style of the text subtitle region including anoverall font-related style of the text data, and inline (local) styleinformation for applying a different font-related style to a selectedportion of the text data.

The apparatus further includes a driver (e.g., a servo) 14 whichcontrols operation of the pickup unit 1, a signal processor 13 whichrestores a signal received from the pickup unit 11 or modulates a signalinto a recordable signal, a memory 15 which stores reproduction controlinformation included in the text subtitle streams, and a microprocessor16 which controls operations of the driver 14, the signal processor 13,and the memory 15.

The apparatus shown in FIG. 7 further includes an AV decoder 17 decodingthe AV signal received from the signal processor 13, and an AV encoder18 converting an input AV signal into a signal having a particularformat, such as MPEG2 transport streams, and transmitting the convertedsignal to the signal processor 13. In addition, the apparatus furtherincludes a controller 12, which controls operations of the signalprocessor 13, the AV decoder 17, and the AV encoder 18.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A text subtitle decoder for decoding a text subtitle stream, the textsubtitle decoder comprising: a text subtitle processor configured toparse the text subtitle stream downloaded from an external source intofirst and second segments, the first segment including region styleinformation including at least one region style to be applied to asubtitle region including text data, the second segment including thetext data to be displayed in the subtitle region and inline styleinformation including at least one font related style to be applied tothe text data, the parsed text data and inline style information beingtransferred to a different area of the text subtitle decoder than theparsed region style information; and a text renderer configured toconvert the text data into bitmap data by rendering the text data withthe region style information and the inline style information undercontrol of a presentation controller, wherein a text subtitle streamfile including the text subtitle stream is separate from a first clipinformation file including attribute information corresponding to thetext subtitle stream file, wherein an AV stream file including an AVstream is separate from a second clip information file includingattribute information corresponding to the AV stream file, the textsubtitle stream file and the AV stream file have one-to-onecorrespondence with the first and the second clip information files,respectively, wherein reproduction of the AV stream is managed by aplayitem, and reproduction of the text subtitle stream is managed by asubplayitem, wherein the playitem indicates beginning and ending timesfor reproduction of the AV stream, and the subplayitem indicatesbeginning and ending times for reproduction of the text subtitle stream,wherein the AV stream file and the text subtitle stream file areseparate files.
 2. The text subtitle decoder of claim 1, wherein the atleast one region style is specified by at least one of a regionposition, a region size, a region background color, a text position, atext flow, a text alignment, a line space, a font identification, a fontstyle, a font size, and a font color defined in the region styleinformation.
 3. The text subtitle decoder of claim 1, wherein the inlinestyle information specifies the specific font-related style byredefining at least one of a font identification (font id), a font style(font style), a font size (font size), and a font color (font color). 4.The text subtitle decoder of claim 1, wherein the text subtitle streamis preloaded before playing back the text subtitle stream.
 5. A methodof decoding a text subtitle stream, the method comprising: parsing thetext subtitle stream downloaded from an external source into firstsegment and second segments, the first segment including region styleinformation including at least one region style to be applied to asubtitle region including text data, the second segment including thetext data to be displayed in the subtitle region and inline styleinformation including at least one font related style to be applied tothe text data, the parsed text data and inline style information beingtransferred to a different area of a text subtitle decoder than theparsed region style information; and converting the text data intobitmap data by rendering the text data with the region style informationand the inline style information, wherein a text subtitle stream fileincluding the text subtitle stream is separate from a first clipinformation file including attribute information corresponding to thetext subtitle stream file, wherein an AV stream file including an AVstream is separate from a second clip information file includingattribute information corresponding to the AV stream file, the textsubtitle stream file and the AV stream file have one-to-onecorrespondence with the first and the second clip information files,respectively, wherein reproduction of the AV stream is managed by aplayitem, and reproduction of the text subtitle stream is managed by asubplayitem, wherein the playitem indicates beginning and ending timesfor reproduction of the AV stream, and the subplayitem indicatesbeginning and ending times for reproduction of the text subtitle stream,wherein the AV stream file and the text subtitle stream file areseparate files.
 6. The method of claim 5, wherein the at least oneregion style- is specified by at least one of a region position, aregion size, a region background color, a text position, a text flow, atext alignment, a line space, a font identification, a font style, afont size, and a font color defined in the region style information. 7.The method of claim 5, wherein the inline style information specifiesthe specific font-related style by redefining at least one of a fontidentification (font id), a font style (font style), a font size (fontsize), and a font color (font color).
 8. The method of claim 5, whereinthe text subtitle stream is preloaded before playing back the textsubtitle stream.
 9. A system for decoding a text subtitle stream, thesystem comprising: a text subtitle decoder configured to parse the textsubtitle stream downloaded from an external source into first and secondsegments, the first segment including region style information includingat least one region style to be applied to a subtitle region includingtext data, the second segment including the text data to be displayed inthe subtitle region and inline style information including at least onefont related style to be applied to the text data, the parsed text dataand inline style information being transferred to a different area of atext subtitle decoder than the parsed region style information, and thetext subtitle decoder further configured to convert the text data intobitmap data by rendering the text data with the inline style informationand region style information under control of a presentation controller;and the presentation controller configured to control a graphic planewhere the bitmap data is displayed and configured to control a colorlook up table where the bitmap data is translated into at least one ofcolor and transparency levels, wherein a text subtitle stream fileincluding the text subtitle stream is separate from a first clipinformation file including attribute information corresponding to thetext subtitle stream file, wherein an AV stream file including an AVstream is separate from a second clip information file includingattribute information corresponding to the AV stream file, the textsubtitle stream file and the AV stream file have one-to-onecorrespondence with the first and the second clip information files,respectively, wherein reproduction of the AV stream is managed by aplayitem, and reproduction of the text subtitle stream is managed by asubplayitem, wherein the playitem indicates beginning and ending timesfor reproduction of the AV stream, and the subplayitem indicatesbeginning and ending times for reproduction of the text subtitle stream,wherein the AV stream file and the text subtitle stream file areseparate files.
 10. The system of claim 9, wherein the at least oneregion style is specified by at least one of a region position, a regionsize, a region background color, a text position, a text flow, a textalignment, a line space, a font identification, a font style, a fontsize, and a font color defined in the region style information.
 11. Thesystem of claim 9, wherein the inline style information specifies thespecific font-related style by redefining at least one of a fontidentification (font id), a font style (font style), a font size (fontsize), and a font color (font color).
 12. The system of claim 9, furthercomprising: a pickup unit configured to read a playlist including theplayitem for managing reproduction of the AV stream and configured toread the subplayitem for managing reproduction of the text subtitlestream; and a subtitle preloading buffer configured to preload the textsubtitle stream managed by the subplayitem included in the playlistbefore playing back the text subtitle stream.
 13. A method of recordinga text subtitle stream in a data storage, the method comprising:recording the text subtitle stream downloaded from an external source,the text subtitle stream including a first segment and a second segment,the first segment including region style information including at leastone region style to be applied to a subtitle region including text data,the second segment including the text data to be displayed in thesubtitle region and inline style information including at least one fontrelated style to be applied to the text data, wherein the region styleinformation and the inline style information are used for a renderingoperation that converts the text data into bitmap data, the recordingrecords a first clip information file including attribute informationcorresponding to a text subtitle stream file including the text subtitlestream and a second clip information file including attributeinformation corresponding to an AV stream file including an AV stream,the text subtitle stream file and the AV stream file have one-to-onecorrespondence with the first and the second clip information files,respectively, wherein reproduction of the AV stream is managed by aplayitem, and reproduction of the text subtitle stream is managed by asubplayitem, wherein the playitem indicates beginning and ending timesfor reproduction of the AV stream, and the subplayitem indicatesbeginning and ending times for reproduction of the text subtitle stream,wherein the AV stream file and the text subtitle stream file areseparate files.
 14. The method of claim 13, wherein the at least oneregion style is specified by at least one of a region position, a regionsize, a region background color, a text position, a text flow, a textalignment, a line space, a font identification, a font style, a fontsize, and a font color defined in the region style information.
 15. Themethod of claim 13, wherein the inline style information specifies thespecific font-related style by redefining at least one of a fontidentification (font id), a font style (font style), a font size (fontsize), and a font color (font color).
 16. An apparatus for recording atext subtitle stream in a data storage, the apparatus comprising: arecording unit configured to record data; and a controller configured tocontrol the recording unit to record the text subtitle stream downloadedfrom an external source, the text subtitle stream including a firstsegment and a second segment, the first segment including region styleinformation including at least one region style to be applied to asubtitle region including text data, the second segment including thetext data to be displayed in the subtitle region and inline styleinformation including at least one font related style to be applied tothe text data, wherein the region style information and the inline styleinformation are used for a rendering operation that converts the textdata into bitmap data, the controller is further configured to controlthe recording unit to record a first clip information file includingattribute information corresponding to a text subtitle stream fileincluding the text subtitle stream and second clip information fileincluding attribute information corresponding to an AV stream fileincluding an AV stream, the text subtitle stream file and the AV streamfile have one-to-one correspondence with the first and the second clipinformation files, respectively, wherein reproduction of the AV streamis managed by a playitem, and reproduction of the text subtitle streamis managed by a subplayitem, wherein the playitem indicates beginningand ending times for reproduction of the AV stream, and the subplayitemindicates beginning and ending times for reproduction of the textsubtitle stream, wherein the AV stream file and the text subtitle streamfile are separate files.
 17. The apparatus of claim 16, wherein the atleast one region style is specified by at least one of a regionposition, a region size, a region background color, a text position, atext flow, a text alignment, a line space, a font identification, a fontstyle, a font size, and a font color defined in the region styleinformation.
 18. The apparatus of claim 16, wherein the inline styleinformation specifies the specific font-related style by redefining atleast one of a font identification (font id), a font style (font style),a font size (font size), and a font color (font color).
 19. Theapparatus of claim 16, wherein the recording unit includes a pickup.